The value of the positron emission tomography camera for allowing in vivo regional quantitative measurement of biochemistry and function in organs of animals and humans is well known as set forth in patent application Ser. No. 396,098, filed July 7, 1982, entitled Three-Dimensional Time-of-Flight Positron Emission Camera System, and patent application Serial No. 613,699, filed May 24, 1984, entitled Positron Emission Tomography Camera.
Conventional positron cameras are extremely expensive, the intrinsic resolution for off-center points is degraded, and the cameras of conventional design require wobbling of the detector ring in order to obtain adequate sampling, which requires expensive and complicated equipment and controls.
The present invention is directed to a positron emission camera (PET) which will provide a small, inexpensive, highly sensitive, motionless camera of greater image sharpness than is provided by conventional designs.
The present invention is directed to a positron emission tomography camera having multiple layers of scintillators with each layer staggered from its adjacent layer. The thickness of each detector is less than that of a conventional detector and allows an improvement in the resolution. The structure reduces the angulation degradation thereby allowing the diameter of the detector ring to be reduced which in turn increases the camera sensitivity and reduces detector costs. The multiple layers of staggered detectors greatly increases the number of samples detected and allows the elimination of the wobble function from the camera.
Another object of the present invention is the provision of a PET camera having a patient area, and a plurality of detector rings positioned side by side around the patient area to detect radiation from a patient in the patient area. Each ring contains a plurality of scintillation detectors directed toward the patient area for defining a plane slice through the patient area by the detectors in each ring. Each ring includes multiple layers of scintillation detectors, the detectors in one of the layers being offset relative to the detectors in the other layers in a ring. Means for converting the detected radiation into electrical pulses is provided adjacent each ring but offset from each ring. The means are directed perpendicular to the plane of the adjacent rings.
Still another object of the present invention is wherein the converting means may be tube photomultipliers or silicon avalanche photomultipliers.
Still a further object of the present invention is wherein the depth of each ring of the detector is sufficient to stop radiation but the depth of each layer of the ring is less than the depth of the ring whereby the angular degradation of the image resolution is reduced.
Other and further objects, features and advantages will be apparent from the following description of a present preferred embodiment of the invention, given for the purpose of disclosure and taken in conjunction with the accompanying drawings.